Chemical compounds

ABSTRACT

The present invention features compounds that are prodrugs of HIIV integrase inhibitors and therefore are useful in the inhibition of HIV replication, the prevention and/or treatment of infection by HIV, and in the treatment of AIDS and/or ARC.

BACKGROUND OF THE INVENTION

The human immunodeficiency virus (“HIV”) is the causative agent foracquired immunodeficiency syndrome (“AIDS”), a disease characterized bythe destruction of the immune system, particularly of CD4⁺ T-cells, withattendant susceptibility to opportunistic infections, and its precursorAIDS-related complex (“ARC”), a syndrome characterized by symptoms suchas persistent generalized lymphadenopathy, fever and weight loss. HIV isa retrovirus; the conversion of its RNA to DNA is accomplished throughthe action of the enzyme reverse transcriptase. Compounds that inhibitthe function of reverse transcriptase inhibit replication of HIV ininfected cells. Such compounds are useful in the prevention or treatmentof HIV infection in humans.

A required step in HIV replication in human T-cells is the insertion byvirally-encoded integrase of proviral DNA into the host cell genome.Integration is believed to be mediated by integrase in a processinvolving assembly of a stable nucleoprotein complex with viral DNAsequences, cleavage of two nucleotides from the 3′ termini of the linearproviral DNA and covalent joining of the recessed 3′ OH termini of theproviral DNA at a staggered cut made at the host target site. The repairsynthesis of the resultant gap may be accomplished by cellular enzymes.

There is continued need to find new therapeutic agents to treat humandiseases. HIV integrase is an attractive target for the discovery of newtherapeutics due to its important role in viral infections, particularlyHIV infections. Integrase inhibitors are disclosed in WO2006/116724.Integrase inhibitors are disclosed in WO2006/116724. The compounds ofthe present invention were designed to deliver active therapeuticagents.

SUMMARY OF THE INVENTION

The present invention features compounds that are prodrugs of HIVintegrase inhibitors and therefore are useful in the inhibition of HIVreplication, the prevention and/or treatment of infection by HIV, and inthe treatment of AIDS and/or ARC. The present invention featurescompounds of formula (I):

wherein:R¹ is C₁-C₈alkyl or LR²;L is alkylene;

R² is

a) hydroxy;b) alkoxy;c) OR³ wherein R³ is P(O)(OH)₂ or alkoxy;d) heterocyclyl optionally substituted with oxo or C₁-C₈alkyl;e) C(O)OR⁴ wherein R⁴ is H, C₁-C₈alkyl, or XR⁵ wherein X is alkylene andR⁵ is C₈-C₁₀aryl, heterocyclyl, or NR⁶R⁷ wherein R⁶ and R⁷ areindependently selected from the group consisting of H and C₁-C₈alkyl;

f) NR⁶R7⁷;

g) C(O)NR⁸R⁹ wherein R⁸ and R⁹ are independently selected from the groupconsisting of H and XR⁵; orh) C(O)R¹⁰ wherein R¹⁰ is heterocyclyl optionally substituted with XR¹¹wherein R¹¹ is heterocyclyl;or a pharmaceutically acceptable salt thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Plasma concentrations of:(4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide(compound 1a of Scheme 2) and a prodrug, Example 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention features compounds of formula (I):

wherein:R¹ is C₁-C₈alkyl or LR²;L is alkylene;

R² is

a) hydroxy;b) alkoxy;c) OR³ wherein R³ is P(O)(OH)₂ or alkoxy;d) heterocyclyl optionally substituted with oxo or C₁-C₈alkyl;e) C(O)OR⁴ wherein R⁴ is H, C₁-C₈alkyl, or XR⁵ wherein X is alkylene andR⁵ is C₈-C₁₀aryl, heterocyclyl, or NR⁶R⁷ wherein R⁶ and R⁷ areindependently selected from the group consisting of H and C₁-C₈alkyl;

f) NR⁶R7⁷;

g) C(O)NR⁸R⁹ wherein R⁸ and R⁹ are independently selected from the groupconsisting of H and XR⁵; orh) C(O)R¹⁰ wherein R¹⁰ is heterocyclyl optionally substituted with XR¹¹wherein R¹¹ is heterocyclyl;or a pharmaceutically acceptable salt thereof.

The present invention also features compounds of formula (I) wherein R¹is C₁₋₈alkyl or a pharmaceutically acceptable salt thereof.

The present invention also features compounds of formula (I) wherein R¹is LR² wherein L is C₁₋₈alkylene and R² is hydroxy, or apharmaceutically acceptable salt thereof.

The present invention also features compounds of formula (I) wherein R¹is LR² wherein L is C₁₋₈alkylene and R² and —OP(O)(OH)₂ or apharmaceutically acceptable salt thereof.

The present invention also features compounds of formula (I) wherein R¹is LR² wherein L is C₁₋₈alkylene and R² and heterocyclyl or apharmaceutically acceptable salt thereof.

The present invention also features compounds of formula (I) selectedfrom the group consisting of:

-   {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl    methyl carbonate;-   {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl    2-(methyloxy)ethyl carbonate;-   {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl    2-hydroxyethyl carbonate;-   {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl    2-(phosphonooxy)ethyl carbonate;-   {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl    2-(4-morpholinyl)ethyl carbonate; and    pharmaceutically acceptable salts thereof.

The term “alkyl”, alone or in combination with any other term, refers toa straight-chain or branched-chain saturated aliphatic hydrocarbonradical containing the specified number of carbon atoms. Examples ofalkyl radicals include, but are not limited to, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl,n-hexyl and the like.

The term “alkylene” refers to a straight or branched chain divalenthydrocarbon radical, preferably having from one to twelve carbon atoms,unless otherwise defined. Examples of “alkylene” as used herein include,but are not limited to, methylene, ethylene, propylene, butylene,isobutylene and the like.

The term “alkoxy” refers to an alkyl ether radical, wherein the term“alkyl” is defined above. Examples of suitable alkyl ether radicalsinclude, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy,n-butoxy, isobutoxy, sec-butoxy, tert-butoxy and the like.

The term “aryl” alone or in combination with any other term, refers to acarbocyclic aromatic moiety (such as phenyl or naphthyl) containing thespecified number of carbon atoms, preferably from 6-10 carbon atoms.Examples of aryl radicals include, but are not limited to, phenyl,naphthyl, indenyl, azulenyl, fluorenyl, anthracenyl, phenanthrenyl,tetrahydronaphthyl, indanyl, phenanthridinyl and the like. Unlessotherwise indicated, the term “aryl” also includes each possiblepositional isomer of an aromatic hydrocarbon radical, such as in1-naphthyl, 2-naphthyl, 5-tetrahydronaphthyl, 6-tetrahydronaphthyl,1-phenanthridinyl, 2-phenanthridinyl, 3-phenanthridinyl,4-phenanthridinyl, 7-phenanthridinyl, 8-phenanthridinyl,9-phenanthridinyl and 10-phenanthridinyl. Examples of aryl radicalsinclude, but are not limited to, phenyl, naphthyl, indenyl, azulenyl,fluorenyl, anthracenyl, phenanthrenyl, tetrahydronaphthyl, indanyl,phenanthridinyl and the like.

The term “heterocycle,” “heterocyclic,” and “heterocyclyl” as usedherein, refer to a 3- to 7-membered monocyclic heterocyclic ring or 8-to 11-membered bicyclic heterocyclic ring system any ring of which iseither saturated, partially saturated or unsaturated, and which may beoptionally benzofused if monocyclic. Each heterocycle consists of one ormore carbon atoms and from one to four heteroatoms selected from thegroup consisting of N, O and S, and wherein the nitrogen and sulfurheteroatoms may optionally be oxidized, and the nitrogen atom mayoptionally be quaternized, and including any bicyclic group in which anyof the above-defined heterocyclic rings is fused to a benzene ring. Theheterocyclic ring may be attached at any carbon or heteroatom, providedthat the attachment results in the creation of a stable structure.Preferred heterocycles include 5-7 membered monocyclic heterocycles and8-10 membered bicyclic heterocycles. When the heterocyclic ring hassubstituents, it is understood that the substituents may be attached toany atom in the ring, whether a heteroatom or a carbon atom, providedthat a stable chemical structure results. “Heteroaromatics” or“heteroaryl” are included within the heterocycles as defined above andgenerally refers to a heterocycle in which the ring system is anaromatic monocyclic or polycyclic ring radical containing five to twentycarbon atoms, preferably five to ten carbon atoms, in which one or morering carbons, preferably one to four, are each replaced by a heteroatomsuch as N, O, S and P. Preferred heteroaryl groups include 5-6 memberedmonocyclic heteroaryls and 8-10 membered bicyclic heteroaryls. Alsoincluded within the scope of the term “heterocycle, “heterocyclic” or“heterocyclyl” is a group in which a non-aromatic heteroatom-containingring is fused to one or more aromatic rings, such as in an indolinyl,chromanyl, phenanthridinyl or tetrahydro-quinolinyl, where the radicalor point of attachment is on the non-aromatic heteroatom-containingring. Unless otherwise indicated, the term “heterocycle, “heterocyclic”or “heterocyclyl” also included each possible positional isomer of aheterocyclic radical, such as in 1-indolinyl, 2-indolinyl, 3-indolinyl.Examples of heterocycles include imidazolyl, imidazolinoyl,imidazolidinyl, quinolyl, isoquinolyl, indolyl, indazolyl,indazolinolyl, perhydropyridazyl, pyridazyl, pyridyl, pyrrolyl,pyrrolinyl, pyrrolidinyl, pyrazolyl, pyrazinyl, quinoxolyl, piperidinyl,pyranyl, pyrazolinyl, piperazinyl, pyrimidinyl, pyridazinyl,morpholinyl, thiamorpholinyl, furyl, thienyl, triazolyl, thiazolyl,carbolinyl, tetrazolyl, thiazolidinyl, benzofuranoyl, thiamorpholinylsulfone, oxazolyl, oxadiazolyl, benzoxazolyl, oxopiperidinyl,oxopyrrolidinyl, oxoazepinyl, azepinyl, isoxozolyl, isothiazolyl,furazanyl, tetrahydropyranyl, tetrahydrofuranyl, thiazolyl, thiadiazoyl,dioxolyl, dioxinyl, oxathiolyl, benzodioxolyl, dithiolyl, thiophenyl,tetrahydrothiophenyl, sulfolanyl, dioxanyl, dioxolanyl,tetahydrofurodihydrofuranyl, tetrahydropyranodihydrofuranyl,dihydropyranyl, tetradyrofurofuranyl and tetrahydropyranofuranyl.

The term “heteroatom” means nitrogen, oxygen, or sulfur and includes anyoxidized form of nitrogen, such as N(O) {N⁺—O⁻} and sulfur such as S(O)and S(O)₂, and the quaternized form of any basic nitrogen.

A combination of substituents or variables is permissible only if such acombination results in a stable or chemically feasible compound

Unless otherwise stated, structures depicted herein are also meant toinclude all stereochemical forms of the structure, i.e., the R and Sconfigurations for each asymmetric center. Therefore, racemates andracemic mixtures, single enantiomers, diastereomeric mixtures andindividual diastereoisomers of the present compounds are expresslyincluded within the scope of the invention. Although the specificcompounds exemplified herein may be depicted in a particularstereochemical configuration, compounds having either the oppositestereochemistry at any given chiral center or mixtures thereof are alsoenvisioned.

Unless otherwise stated, structures depicted herein are also meant toinclude compounds which differ only in the presence of one or moreisotopically enriched atoms. For example, compounds having the presentstructures except for the replacement of a hydrogen by a deuterium ortritium, or the replacement of a carbon by a ¹³C- or ¹⁴C-enriched carbonare also within the scope of this invention.

It will be apparent to one skilled in the art that certain compounds ofthis invention may exist in alternative tautomeric forms. All suchtautomeric forms of the present compounds are within the scope of theinvention. Unless otherwise indicated, the representation of eithertautomer is meant to include the other.

The term “pharmaceutically effective amount” refers to an amounteffective in treating a virus infection, for example an HIV infection,in a patient either as monotherapy or in combination with other agents.The term “treating” as used herein refers to the alleviation of symptomsof a particular disorder in a patient, or the improvement of anascertainable measurement associated with a particular disorder, and mayinclude the suppression of symptom recurrence in an asymptomatic patientsuch as a patient in whom a viral infection has become latent. The term“prophylactically effective amount” refers to an amount effective inpreventing a virus infection, for example an HIV infection, orpreventing the occurrence of symptoms of such an infection, in apatient. As used herein, the term “patient” refers to a mammal,including a human.

The term “pharmaceutically acceptable carrier or adjuvant” refers to acarrier or adjuvant that may be administered to a patient, together witha compound of this invention, and which does not destroy thepharmacological activity thereof and is nontoxic when administered indoses sufficient to deliver a therapeutic amount of the antiviral agent.

The term “treatment” as used herein refers to the alleviation ofsymptoms of a particular disorder in a patient, or the improvement of anascertainable measurement associated with a particular disorder, and mayinclude the suppression of symptom recurrence in an asymptomatic patientsuch as a patient in whom a viral infection has become latent. Treatmentincludes prophylaxis which refers to preventing a disease or conditionor preventing the occurrence of symptoms of such a disease or condition,in a patient. As used herein, the term “patient” refers to a mammal,including a human.

As used herein, the term “subject” refers to a patient, animal or abiological sample. The term “biological sample”, as used herein,includes, without limitation, cell cultures or extracts thereof;preparations of an enzyme suitable for in vitro assay; biopsied materialobtained from a mammal or extracts thereof; and blood, saliva, urine,feces, semen, tears, or other body fluids or extracts thereof.

Pharmaceutically acceptable salts of the compounds according to theinvention include those derived from pharmaceutically acceptableinorganic and organic acids and bases. Examples of suitable acidsinclude hydrochloric, hydrobromic, sulfuric, nitric, perchloric,fumaric, maleic, phosphoric, glycollic, lactic, salicyclic, succinic,toluene-p-sulfonic, tartaric, acetic, citric, methanesulfonic,ethanesulfonic, formic, benzoic, malonic, naphthalene-2-sulfonic andbenzenesulfonic acids. Other acids, such as oxalic, while not inthemselves pharmaceutically acceptable, may be employed in thepreparation of salts useful as intermediates in obtaining the compoundsof the invention and their pharmaceutically acceptable acid additionsalts.

Salts derived from appropriate bases include alkali metal (e.g. sodium),alkaline earth metal (e.g., magnesium), ammonium, NW₄ ⁺ (wherein W isC₁₋₄ alkyl) and other amine salts. Physiologically acceptable salts of ahydrogen atom or an amino group include salts or organic carboxylicacids such as acetic, lactic, tartaric, malic, isethionic, lactobionicand succinic acids; organic sulfonic acids such as methanesulfonic,ethanesulfonic, benzenesulfonic and p-toluenesulfonic acids andinorganic acids such as hydrochloric, sulfuric, phosphoric and sulfamicacids. Physiologically acceptable salts of a compound with a hydroxygroup include the anion of said compound in combination with a suitablecation such as Na⁺, NH₄ ⁺, and NW₄ ⁺ (wherein W is a C₁₋₄alkyl group).Preferred salts include sodium, calcium, potassium and hydrochloride.

Other compounds of this invention may be prepared by one skilled in theart following the teachings of the specification coupled with knowledgein the art using reagents that are readily synthesized or commerciallyavailable.

Any reference to any of the above compounds also includes a reference toa pharmaceutically acceptable salt thereof.

Salts of the compounds of the present invention may be made by methodsknown to a person skilled in the art. For example, treatment of acompound of the present invention with an appropriate base or acid in anappropriate solvent will yield the corresponding salt.

Compounds of the present invention are useful as prodrugs to delivertherapeutic compounds, for examples compounds disclosed inWO2006/116764, which were demonstrated to have HIV integrase inhibitoryactivity. One aspect of the instant invention relates to methods oftreating or preventing viral infection, for example an HIV infection, ina biological sample comprising contacting the biological sample withcompounds of formula (I) or pharmaceutically acceptable salts thereof.Another aspect of the instant invention relates to methods of treatingor preventing viral infection, for example, an HIV infection, in apatient comprising administering to the patient a therapeuticallyeffective amount of compounds of formula (I) or (Ia) or pharmaceuticallyacceptable salts thereof.

The compounds according to the invention are particularly suited to thetreatment or prophylaxis of HIV infections and associated conditions.Reference herein to treatment extends to prophylaxis as well as thetreatment of established infections, symptoms, and associated clinicalconditions such as AIDS related complex (ARC), Kaposi's sarcoma, andAIDS dementia.

According to one embodiment of the invention, compounds of formula (I)or salts thereof may be formulated into compositions. In a preferredembodiment, the composition is a pharmaceutical composition, whichcomprises a compound of formula (I) and pharmaceutically acceptablecarrier, adjuvant or vehicle. In one embodiment, the compositioncomprises an amount of a compound of the present invention effective totreat or prevent viral infection, for example an HIV infection, in abiological sample or in a patient. In another embodiment, compounds ofthis invention and pharmaceutical compositions thereof, which comprisean amount of a compound of the present innovation effective to inhibitviral replication or to treat or prevent a viral infection or disease ordisorder, for example an HIV infection, and a pharmaceuticallyacceptable carrier, adjuvant or vehicle, may be formulated foradministration to a patient, for example, for oral administration.

The present invention features compounds according to the invention foruse in medical therapy, for example for the treatment or prophylaxis ofa viral infection, for example an HIV infection and associatedconditions. The compounds according to the invention are especiallyuseful for the treatment of AIDS and related clinical conditions such asAIDS related complex (ARC), progressive generalized lymphadenopathy(PGL), Kaposi's sarcoma, thrombocytopenic purpura, AIDS-relatedneurological conditions such as AIDS dementia complex, multiplesclerosis or tropical paraperesis, anti-HIV antibody-positive andHIV-positive conditions, including such conditions in asymptomaticpatients.

According to another aspect, the present invention provides a method forthe treatment or prevention of the symptoms or effects of a viralinfection in an infected patient, for example, a mammal including ahuman, which comprises administering to said patient a pharmaceuticallyeffective amount of a compound according to the invention. According toone aspect of the invention, the viral infection is a retroviralinfection, in particular an HIV infection.

The present invention further includes the use of a compound accordingto the invention in the manufacture of a medicament for administrationto a subject for the treatment of a viral infection, in particular andHIV infection.

The compounds according to the invention may also be used in adjuvanttherapy in the treatment of HIV infections or HIV-associated symptoms oreffects, for example Kaposi's sarcoma.

The present invention further provides a method for the treatment of aclinical condition in a patient, for example, a mammal including a humanwhich clinical condition includes those which have been discussedhereinbefore, which comprises treating said patient with apharmaceutically effective amount of a compound according to theinvention. The present invention also includes a method for thetreatment or prophylaxis of any of the aforementioned diseases orconditions.

Reference herein to treatment extends to prophylaxis as well as thetreatment of established conditions, disorders and infections, symptomsthereof, and associated. The above compounds according to the inventionand their pharmaceutically acceptable salts may be employed incombination with other therapeutic agents for the treatment of the aboveinfections or conditions. Combination therapies according to the presentinvention comprise the administration of a compound of the presentinvention or a pharmaceutically acceptable salt thereof and anotherpharmaceutically active agent. The active ingredient(s) andpharmaceutically active agents may be administered simultaneously (i.e.,concurrently) in either the same or different pharmaceuticalcompositions or sequentially in any order. The amounts of the activeingredient(s) and pharmaceutically active agent(s) and the relativetimings of administration will be selected in order to achieve thedesired combined therapeutic effect.

-   -   Examples of other therapeutic agents include:    -   Nucleotide reverse transcriptase inhibitors such as zidovudine,        didanosine, lamivudine, zalcitabine, abacavir, stavidine,        adefovir, adefovir dipivoxil, fozivudine, todoxil,        emtricitabine, alovudine, amdoxovir, elvucitabine, and similar        agents;    -   Non-nucleotide reverse transcriptase inhibitors (including an        agent having anti-oxidation activity such as immunocal,        oltipraz, etc.) such as nevirapine, delavirdine, efavirenz,        loviride, immunocal, oltipraz, capravirine, TMC-278, TMC-125,        etravirine, and similar agents;    -   Protease inhibitors such as saquinavir, ritonavir, indinavir,        nelfinavir, amprenavir, fosamprenavir, brecanavir, raltegravir,        atazanavir, tipranavir, palinavir, lasinavir, and similar        agents;    -   Entry inhibitors such as enfuvirtide (T-20), T-1249, PRO-542,        PRO-140, TNX-355, BMS-806, 5-Helix and similar agents;    -   Integrase inhibitors such as L-870,810, raltegravir and similar        agents;    -   Budding inhibitors such as PA-344 and PA-457, and similar        agents; and    -   CXCR4 and/or CCR5 inhibitors such as vicriviroc (Sch-C), Sch-D,        TAK779, maraviroc (UK 427,857), TAK449 and similar agents.

The present invention further includes the use of a compound accordingto the invention in the manufacture of a medicament for simultaneous orsequential administration with at least another therapeutic agent, suchas those defined hereinbefore.

Compounds of the present invention may be administered with an agentknown to inhibit or reduce the metabolism of compounds, for exampleritonavir. Accordingly, the present invention features a method for thetreatment or prophylaxis of a disease as hereinbefore described byadministration of a compound of the present invention in combinationwith a metabolic inhibitor. Such combination may be administeredsimultaneously or sequentially.

In general a suitable dose for each of the above-mentioned conditionswill be in the range of 0.01 to 250 mg per kilogram body weight of therecipient (e.g. a human) per day, preferably in the range of 0.01 to 100mg per kilogram body weight per day. Unless otherwise indicated, allweights of active ingredient are calculated as the parent compound offormula (I); for salts or esters thereof, the weights would be increasedproportionally. The desired dose may be presented as one, two, three,four, five, six or more sub-doses administered at appropriate intervalsthroughout the day. In some cases the desired dose may be given onalternative days. These sub-doses may be administered in unit dosageforms, for example, containing 1 to 1000 mg, 20 to 500 mg, 10 to 500 mg,or 1 to 400 mg of active ingredient per unit dosage form.

While it is possible for the active ingredient to be administered alone,it is preferable to present it as a pharmaceutical composition. Thecompositions of the present invention comprise at least one activeingredient, as defined above, together with one or more acceptablecarriers thereof and optionally other therapeutic agents. Each carriermust be acceptable in the sense of being compatible with the otheringredients of the composition and not injurious to the patient.

Pharmaceutical compositions include those suitable for oral, rectal,nasal, topical (including transdermal, buccal and sublingual), vaginalor parenteral (including subcutaneous, intramuscular, intravenous,intradermal, and intravitreal) administration. The compositions mayconveniently be presented in unit dosage form and may be prepared by anymethods well known in the art of pharmacy. Such methods represent afurther feature of the present invention and include the step ofbringing into association the active ingredients with the carrier, whichconstitutes one or more accessory ingredients. In general, thecompositions are prepared by uniformly and intimately bringing intoassociation the active ingredients with liquid carriers or finelydivided solid carriers or both, and then if necessary shaping theproduct.

The present invention further includes a pharmaceutical composition ashereinbefore defined wherein a compound of the present invention or apharmaceutically acceptable salt thereof and another therapeutic agentare presented separately from one another as a kit of parts.

Compositions suitable for transdermal administration may be presented asdiscrete patches adapted to remain in intimate contact with theepidermis of the recipient for a prolonged period of time. Such patchessuitably contain the active compound 1) in an optionally buffered,aqueous solution or 2) dissolved and/or dispersed in an adhesive or 3)dispersed in a polymer. A suitable concentration of the active compoundis about 1% to 25%, preferably about 3% to 15%. As one particularpossibility, the active compound may be delivered from the patch byelectrotransport or iontophoresis as generally described inPharmaceutical Research 3(6), 318 (1986).

Pharmaceutical compositions of the present invention suitable for oraladministration may be presented as discrete units such as capsules,caplets, cachets or tablets each containing a predetermined amount ofthe active ingredients; as a powder or granules; as a solution or asuspension in an aqueous or non-aqueous liquid; or as an oil-in-waterliquid emulsion or a water-in-oil liquid emulsion. The active ingredientmay also be presented as a bolus, electuary or paste.

A tablet may be made by compression or molding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active ingredients in afree-flowing form such as a powder or granules, optionally mixed with abinder (e.g. povidone, gelatin, hydroxypropylmethyl cellulose),lubricant, inert diluent, preservative, disintegrant (e.g. sodium starchglycollate, cross-linked povidone, cross-linked sodium carboxymethylcellulose) surface-active or dispersing agent. Molded tablets may bemade by molding a mixture of the powdered compound moistened with aninert liquid diluent in a suitable machine. The tablets may optionallybe coated or scored and may be formulated so as to provide slow orcontrolled release of the active ingredients therein using, for example,hydroxypropylmethyl cellulose in varying proportions to provide thedesired release profile. Tablets may optionally be provided with anenteric coating, to provide release in parts of the gut other than thestomach.

Pharmaceutical compositions suitable for topical administration in themouth include lozenges comprising the active ingredients in a flavoredbase, usually sucrose and acacia or tragacanth; pastilles comprising theactive ingredient in an inert basis such as gelatin and glycerin, orsucrose and acacia; and mouthwashes comprising the active ingredient ina suitable liquid carrier.

Pharmaceutical compositions suitable for vaginal administration may bepresented as pessaries, tampons, creams, gels, pastes, foams or spray.Pharmaceutical compositions may contain in addition to the activeingredient such carriers as are known in the art to be appropriate.

Pharmaceutical compositions for rectal administration may be presentedas a suppository with a suitable carrier comprising, for example, cocoabutter or a salicylate or other materials commonly used in the art. Thesuppositories may be conveniently formed by admixture of the activecombination with the softened or melted carrier(s) followed by chillingand shaping in molds.

Pharmaceutical compositions suitable for parenteral administrationinclude aqueous and nonaqueous isotonic sterile injection solutionswhich may contain anti-oxidants, buffers, bacteriostats and soluteswhich render the pharmaceutical composition isotonic with the blood ofthe intended recipient; and aqueous and non-aqueous sterile suspensionswhich may include suspending agents and thickening agents; and liposomesor other microparticulate systems which are designed to target thecompound to blood components or one or more organs. The pharmaceuticalcompositions may be presented in unit-dose or multi-dose sealedcontainers, for example, ampoules and vials, and may be stored in afreeze-dried (lyophilized) condition requiring only the addition of thesterile liquid carrier, for example water for injection, immediatelyprior to use. Extemporaneous injection solutions and suspensions may beprepared from sterile powders, granules and tablets of the kindpreviously described.

Unit dosage pharmaceutical compositions include those containing a dailydose or daily subdose of the active ingredients, as hereinbeforerecited, or an appropriate fraction thereof.

It should be understood that in addition to the ingredients particularlymentioned above the pharmaceutical compositions of this invention mayinclude other agents conventional in the art having regard to the typeof pharmaceutical composition in question, for example, those suitablefor oral administration may include such further agents as sweeteners,thickeners and flavoring agents.

The compounds of the present invention may be prepared according to thefollowing reactions schemes and examples, or modifications thereof usingreadily available starting materials, reagents and conventionalsynthesis procedures. In these reactions, it is also possible to makeuse of variants which are known to those of ordinary skill in the art.

(4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamidecan be prepared by methods known to those skilled in the art, includingmethods disclosed in WO2006/116724.

The following examples are intended for illustration only and are notintended to limit the scope of the invention in any way.

Preparation 1:(4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamidesodium salt (compound 1b, scheme 2)

-   -   a) Synthesis of 2-methyl-3-[(phenylmethyl)oxy]-4H-pyran-4-one        (compound P-2). To a slurry of 2000 g of compound P-1 (1.0 eq.)        in 14.0 L of MeCN were added 2848 g of benzyl bromide (1.05 eq.)        and 2630 g of K₂CO₃ (1.2 eq.). The mixture was stirred at 80° C.        for 5 h and cooled to 13° C. Precipitate was filtered and washed        with 5.0 L of MeCN. The filtrate was concentrated and 3.0 L of        THF was added to the residue. The THF solution was concentrated        to give 3585 g of crude compound P-2 as oil. Without further        purification, compound P-2 was used in the next step. ¹H NMR        (300 MHz, CDCl₃) δ 7.60 (d, J=5.7 Hz, 1H), 7.4-7.3 (m, 5H), 6.37        (d, J=5.7 Hz, 1H), 5.17 (s, 2H), 2.09 (s, 3H).    -   b) Synthesis of        2-(2-hydroxy-2-phenylethyl)-3-[(phenylmethyl)oxy]-4H-pyran-4-one        (compound P-3). To 904 g of the crude compound P-2 was added        5.88 L of THF and the solution was cooled to −60° C. 5.00 L of        1.0 M of Lithium bis(trimethylsilylamide) in THF (1.25 eq.) was        added dropwise for 2 h to the solution of compound 2 at −60° C.        Then, a solution of 509 g of benzaldehyde (1.2 eq.) in 800 mL of        THF was added at −60° C. and the reaction mixture was aged at        −60° C. for 1 h. The THF solution was poured into a mixture of        1.21 L of conc. HCl, 8.14 L of ice water and 4.52 L of EtOAc at        less than 2° C. The organic layer was washed with 2.71 L of        brine (twice) and the aqueous layer was extracted with 3.98 L of        EtOAc. The combined organic layers were concentrated. To the        mixture, 1.63 L of toluene was added and concentrated (twice) to        provide toluene slurry of compound P-3. Filtration, washing with        0.90 L of cold toluene and drying afforded 955 g of compound P-3        (74% yield from compound P-1) as a solid. ¹H NMR (300 MHz,        CDCl₃) δ 7.62 (d, J=5.7 Hz, 1H), 7.5-7.2 (m, 10H), 6.38 (d,        J=5.7 Hz, 1H), 5.16 (d, J=11.4 Hz, 1H), 5.09 (d, J=11.4 Hz, 1H),        4.95 (dd, J=4.8, 9.0 Hz, 1H), 3.01 (dd, J=9.0, 14.1 Hz, 1H),        2.84 (dd, J=4.8, 14.1 Hz, 1H).    -   c) Synthesis of        2-[(E)-2-phenylethenyl]-3-[(phenylmethyl)oxy]-4H-pyran-4-one        (compound P-4). To a solution of 882 g of compound P-3 (1.0 eq.)        in 8.82 L of THF were added 416 g of Et₃N (1.5 eq.) and 408 g of        methanesulfonyl chloride (1.3 eq.) at less than 30° C. After        confirmation of disappearance of compound P-3, 440 mL of NMP and        1167 g of DBU (2.8 eq.) were added to the reaction mixture at        less than 30° C. and the reaction mixture was aged for 30 min.        The mixture was neutralized with 1.76 L of 16% sulfuric acid and        the organic layer was washed with 1.76 L of 2% Na₂SO₃aq. After        concentration of the organic layer, 4.41 L of toluene was added        and the mixture was concentrated (tree times). After addition of        4.67 L of hexane, the mixture was cooled with ice bath.        Filtration, washing with 1.77 L of hexane and drying provided        780 g of compound P-4 (94% yield) as a solid. ¹H NMR (300 MHz,        CDCl₃) δ 7.69 (d, J=5.7 Hz, 1H), 7.50-7.25 (m, 10H), 7.22 (d,        J=16.2 Hz, 1H), 7.03 (d, J=16.2 Hz, 1H), 6.41 (d, J=5.7 Hz, 1H),        5.27 (s, 2H).    -   d) Synthesis of        4-oxo-3-[(phenylmethyl)oxy]-4H-pyran-2-carboxylic acid (compound        P-5). To a mixture of 822 g of compound P-4 (1.0 eq.) and 11.2 g        of RuCl₃.nH₂O (0.02 eq.) in 2.47 L of MeCN, 2.47 L of EtOAc and        2.47 L of H₂O was added 2310 g of NaIO₄ (4.0 eq.) at less than        25° C. After aging for 1 h, 733 g of NaClO₂ (3.0 eq.) was added        to the mixture at less than 25° C. After aging for 1 h,        precipitate was filtered and washed with 8.22 L of EtOAc. To the        filtrate, 1.64 L of 50% Na₂S₂O₃aq, 822 mL of H₂O and 630 mL of        coc.HCl were added. The aqueous layer was extracted with 4.11 L        of EtOAc and the organic layers were combined and concentrated.        To the residue, 4 L of toluene was added and the mixture was        concentrated and cooled with ice bath. Filtration, washing with        1 L of toluene and drying provided 372 g of compound P-5 (56%        yield) as a solid. ¹H NMR (300 MHz, CDCl₃) δ 7.78 (d, J=5.7 Hz,        1H), 7.54-7.46 (m, 2H), 7.40-7.26 (m, 3H), 6.48 (d, J=5.7 Hz,        1H), 5.6 (brs, 1H), 5.31 (s, 2H).    -   e) Synthesis of        1-(2,3-dihydroxypropyl)-4-oxo-3-[(phenylmethyl)oxy]-1,4-dihydro-2-pyridinecarboxylic        acid (compound P-6). A mixture of 509 g of compound P-5 (1.0        eq.) and 407 g of 3-amino-propane-1,2-diol (2.5 eq.) in 1.53 L        of EtOH was stirred at 65° C. for 1 h and at 80° C. for 6 h.        After addition of 18.8 g of 3-Amino-propane-1,2-diol (0.1 eq.)        in 200 mL of EtOH, the mixture was stirred at 80° C. for 1 h.        After addition of 18.8 g of 3-amino-propane-1,2-diol (0.1 eq.)        in 200 mL of EtOH, the mixture was stirred at 80° C. for 30 min.        After cooling and addition of 509 mL of H₂O, the mixture was        concentrated. To the residue, 2.54 L of H₂O and 2.54 L of AcOEt        were added. After separation, the aqueous layer was washed with        1.02 L of EtOAc. To the aqueous layer, 2.03 L of 12% sulfuric        acid was added at less than 12° C. to give crystal of compound        P-6. Filtration, washing with 1.53 L of cold H₂O and drying        provided 576 g of compound P-6 (83% yield) as a solid. ¹H NMR        (300 MHz, DMSO-d₆) δ 7.67 (d, J=7.5 Hz, 1H), 7.5-7.2 (m, 5H),        6.40 (d, J=7.5 Hz, 1H), 5.07 (s, 2H), 4.2-4.0 (m, 1H), 3.9-3.6        (m, 2H), 3.38 (dd, J=4.2, 10.8 Hz, 1H), 3.27 (dd, J=6.0, 10.8        Hz, 1H).    -   f) Synthesis of methyl        1-(2,3-dihydroxypropyl)-4-oxo-3-[(phenylmethyl)oxy]-1,4-dihydro-2-pyridinecarboxylate        (compound P-7). To a slurry of 576 g of compound P-6 (1.0 eq.:        5.8% of H₂O was contained) in 2.88 L of NMP were added 431 g of        NaHCO₃ (3.0 eq.) and 160 mL of methyl iodide (1.5 eq.) and the        mixture was stirred at room temperature for 4 h. After cooling        to 5° C., 1.71 L of 2N HCl and 1.15 L of 20% NaClaq were added        to the mixture at less than 10° C. to give crystal of        compound 7. Filtration, washing with 1.73 L of H₂O and drying        provided 507 g of compound P-7 (89% yield) as a solid. ¹H NMR        (300 MHz, DMSO-d₆) δ 7.59 (d, J=7.5 Hz, 1H), 7.40-7.28 (m, 5H),        6.28 (d, J=7.5 Hz, 1H), 5.21 (d, J=5.4 Hz, 1H), 5.12 (d, J=10.8        Hz, 1H), 5.07 (d, J=10.8 Hz, 1H), 4.83 (t, J=5.7 Hz, 1H), 3.97        (dd, J=2.4, 14.1 Hz, 1H), 3.79 (s, 3H), 3.70 (dd, J=9.0, 14.4        Hz, 1H), 3.65-3.50 (m, 1H), 3.40-3.28 (m, 1H), 3.26-3.14 (m,        1H).    -   g) Synthesis of methyl        1-(2,2-dihydroxyethyl)-4-oxo-3-[(phenylmethyl)oxy]-1,4-dihydro-2-pyridinecarboxylate        (compound P-8). To a mixture of 507 g of compound P-7 (1.0 eq.)        in 5.07 L of MeCN, 5.07 L of H₂O and 9.13 g of AcOH (0.1 eq.)        was added 390 g of NaIO₄ (1.2 eq.) and the mixture was stirred        at room temperature for 2 h. After addition of 1.52 L of 10%        Na₂S₂O₃aq., the mixture was concentrated and cooled to 10° C.        Filtration, washing with H₂O and drying provided 386 g of        compound P-8 (80% yield) as a solid. ¹H NMR (300 MHz, DMSO-d₆) δ        7.62 (d, J=7.5 Hz, 1H), 7.42-7.30 (m, 5H), 6.33 (d, J=6.0 Hz,        2H), 6.29 (d, J=7.5 Hz, 1H), 5.08 (s, 2H), 4.95-4.85 (m, 1H),        3.80 (s, 3H), 3.74 (d, J=5.1 Hz, 2H).    -   h) Synthesis of        (4R,12aS)-4-methyl-7-[(phenylmethyl)oxy]-3,4,12,12a-tetrahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione        (compound P-9). After dissolution of a mixture of 378 g of        compound P-8 (1.0 eq.) in 3.78 L of MeOH by heating, the        solution was concentrated. To the residue, 1.51 L of toluene was        added and the mixture was concentrated. To the residue, 1.89 L        of toluene, 378 mL of AcOH and 137 g of (R)-3-Amino-butan-1-ol        (1.3 eq.) were added and the mixture was heated to 90° C.,        stirred at 90° C. for 2.5 h and concentrated. To the residue,        1.89 L of toluene was added and the mixture was concentrated.        The residue was extracted with 3.78 L and 1.89 L of CHCl₃ and        washed with 2×1.89 L of H₂O. The organic layers were combined        and concentrated. To the residue, 1.89 L of EtOAc was added and        the mixture was concentrated. After addition of 1.89 L of EtOAc,        filtration, washing with 1.13 L of EtOAc and drying provided 335        g of compound P-9 (83% yield) as a solid. ¹H NMR (300 MHz,        CDCl₃) δ 7.70-7.58 (m, 2H), 7.40-7.24 (m, 3H), 7.14 (d, J=7.5        Hz, 2H), 6.47 (d, J=7.5 Hz, 1H), 5.35 (d, J=10.2 Hz, 1H), 5.28        (d, J=10.2 Hz, 1H), 5.12 (dd, J=3.9, 6.3 Hz, 1H), 5.05-4.90 (m,        1H), 4.07 (dd, J=3.9, 13.5 Hz, 1H), 4.00-3.86 (m, 3H), 2.23-2.06        (m, 1H), 1.48 (ddd, J=2.4, 4.5, 13.8 Hz, 1H), 1.30 (d, J=6.9 Hz,        3H).    -   i) Synthesis of        (4R,12aS)-9-bromo-4-methyl-7-[(phenylmethyl)oxy]-3,4,12,12a-tetrahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione        (compound P-10). To a slurry of 332 g of compound P-9 (1.0 eq.)        in 1.66 L of NMP was added 191 g of NBS (1.1 eq.) and the        mixture was stirred at room temperature for 2 h. After addition        of 1.26 L of H₂O, the mixture was stirred for 30 min. After        addition of 5.38 L of H₂O and aging of the mixture at 10° C. for        30 min and at 5° C. for 1 h, filtration, washing with 1.33 L of        cold H₂O and drying provided 362 g of compound P-10 (89% yield)        as a solid. ¹H NMR (300 MHz, CDCl₃) δ 7.69-7.63 (m, 2H), 7.59        (s, 1H), 7.38-7.24 (m, 3H), 5.33 (d, J=10.2 Hz, 1H), 5.25 (d,        J=9.9 Hz, 1H), 5.12 (dd, J=3.9, 5.7 Hz, 1H), 5.05-4.90 (m, 1H),        4.11 (dd, J=3.9, 13.2 Hz, 1H), 4.02-3.88 (m, 3H), 2.21-2.06 (m,        1H), 1.49 (ddd, J=2.4, 4.5, 14.1 Hz, 1H), 1.31 (d, J=6.9 Hz,        3H).    -   j) Synthesis of        (4R,12aS)—N-[(2,4-difluorophenyl)methyl]-4-methyl-6,8-dioxo-7-[(phenylmethyl)oxy]-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        (compound P-11). Under carbon mono-oxide atmosphere, a mixture        of 33.5 g of compound P-10 (1.0 eq.), 34.8 mL of i-Pr₂NEt (2.5        eq.), 14.3 mL of 2,4-difluorobenzylamine (1.5 eq.) and 4.62 g of        Pd(PPh₃)₄ (0.05 eq.) in 335 mL of DMSO was stirred at 90° C. for        5.5 h. After cooling, precipitate was filtered and washed with        50 mL of 2-propanol. After addition of 502 mL of H₂O and 670 mL        of AcOEt to the filtrate, the organic layer was washed with 335        mL of 0.5N HClaq. and 335 mL of H₂O and the aqueous layer was        extracted with 335 mL of AcOEt. The organic layers were combined        and concentrated. To the residue, 150 mL of 2-propanol was added        and the mixture was concentrated. After addition of 150 mL of        2-propanol, concentration, cooling to 20° C. and filtration,        crude crystal of compound P-11 was obtained. After dissolution        of the crude crystal in 380 mL of acetone by heating,        precipitate was filtered and the filtrate was concentrated.        After addition of 200 mL of EtOH, concentration, addition of 150        mL of EtOH, concentration, cooling and filtration, crude crystal        of compound P-11 was obtained. After dissolution of the crude        crystal in 450 mL of acetone by heating, the solution was        concentrated. To the residue, 150 mL of 2-propanol was added and        the mixture was concentrated (twice). After cooling of the        residue, filtration, washing with 2-propanol and drying provided        34.3 g of compound P-11 (84% yield) as a solid. ¹H NMR (300 MHz,        CDCl₃) δ 10.40 (t, J=6.0 Hz, 1H), 8.35 (s, 1H), 7.66-7.58 (m,        2H), 7.42-7.24 (m, 5H), 6.78-6.74 (m, 2H), 5.30 (d, J=9.9 Hz,        1H), 5.26 (d, J=10.2 Hz, 1H), 5.15 (dd, J=3.9, 5.7 Hz, 1H),        5.05-4.90 (m, 1H), 4.64 (d, J=5.4 Hz, 2H), 4.22 (dd, J=3.9,        13.5, 1H), 4.09 (dd, J=6.0, 13.2 Hz, 1H), 4.02-3.88 (m, 2H),        2.24-1.86 (m, 1H), 1.50 (ddd, J=2.4, 4.5, 14.1 Hz, 1H), 1.33 (d,        J=7.2 Hz, 3H).    -   k) Synthesis of        (4R,12aS)—N-[(2,4-difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        (compound 1a) Under hydrogen atmosphere, a mixture of 28.0 g of        compound P-11 (1.0 eq.) and 5.6 g of 10% Pd—C in 252 mL of THF        and 28 mL of MeOH was stirred for 1 h. After precipitate (Pd—C)        was filtered and washed with 45 mL of THF, 5.6 g of 10% Pd—C was        added and the mixture was stirred for 1.5 h under hydrogen        atmosphere. After Pd—C was filtered and washed with 150 mL of        CHCl₃/MeOH (9/1), the filtrate was concentrated. After        dissolution of the residue in 1.38 L of EtOH by heating, the        solution was gradually cooled to room temperature. After        filtration, the filtrate was concentrated and cooled.        Filtration, washing with EtOH and drying provided 21.2 g of        compound 1a (92% yield) as a solid. ¹H NMR (300 MHz, DMSO-d₆) δ        12.51 (s, 1H), 10.36 (t, J=5.7 Hz, 1H), 8.50 (s, 1H), 7.39 (td,        J=8.7, 6.3 Hz, 1H), 7.24 (ddd, J=2.6, 9.5, 10.8 Hz, 1H),        7.12-7.00 (m, 1H), 5.44 (dd, J=3.9, 5.7 Hz, 1H), 4.90-4.70 (m,        1H), 4.65-4.50 (m, 1H), 4.54 (d, J=5.1 Hz, 2H), 4.35 (dd, J=6.0,        13.8 Hz, 1H), 4.10-3.98 (m, 1H), 3.96-3.86 (m, 1H), 2.10-1.94        (m, 1H), 1.60-1.48 (m, 1H), 1.33 (d, J=6.9 Hz, 3H).    -   l). Synthesis of        (4R,12aS)—N-[(2,4-difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        sodium salt (compound 1 b). After dissolution of 18.0 g of        compound 1a (1.0 eq.) in 54 mL of EtOH by heating, followed by        filtration, 21.5 mL of 2N NaOHaq. (1.0 eq.) was added to the        solution at 80° C. The solution was gradually cooled to room        temperature. Filtration, washing with 80 mL of EtOH and drying        provided 18.8 g of compound 1b (99% yield) as a solid. ¹H NMR        (300 MHz, DMSO-d₆) δ 10.70 (t, J=6.0 Hz, 1H), 7.89 (s, 1H),        7.40-7.30 (m, 1H), 7.25-7.16 (m, 1H), 7.06-6.98 (m, 1H),        5.22-5.12 (m, 1H), 4.87-4.74 (m, 1H), 4.51 (d, J=5.4 Hz, 2H),        4.35-4.25 (m, 1H), 4.16 (dd, J=1.8, 14.1 Hz, 1H), 4.05-3.90 (m,        1H), 3.86-3.74 (m, 1H), 2.00-1.72 (m, 1H), 1.44-1.32 (m, 1H),        1.24 (d, J=6.9 Hz, 3H).

Example 1{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methylmethyl carbonate

-   -   a) Chloromethyl methyl carbonate. Chloromethyl chloridocarbonate        (3 ml, 33.7 mmol) was dissolved in dichloromethane (10 mL) and        cooled to 0° C. Methanol (1.36 mL, 33.7 mmol) was added        dropwise, followed by pyridine (2.73 mL, 33.7 mmol) dropwise.        The white suspension was stirred at 0° C. and allowed to warm to        ambient temperature and stirred for 14 hours. The suspension was        quenched with water, diluted with aqueous citric acid, extracted        with dichloromethane, washed with sodium bicarbonate, brine,        dried over sodium sulfate and concentrated under reduced        pressure to give chloromethyl methyl carbonate as a clear        colorless oil. ¹H NMR (CDCl₃) δ 5.72 (s, 2H), 3.96 (s, 3H).    -   b) Iodomethyl methyl carbonate. Chloromethyl methyl carbonate        (2.05 g, 16.46 mmol) was dissolved in acetone and sodium iodide        (3.70 g, 24.69 mmol) was added and the reaction was heated at        40° C. for 15 hours. The yellow suspension was allowed to cool        to ambient temperature, concentrated under reduced pressure,        diluted with water and aqueous sodium thiosulfate, extracted        with dichloromethane, washed with brine, dried over sodium        sulfate, and concentrated under reduced pressure to give        iodomethyl methyl carbonate as a clear yellow oil. ¹H NMR        (CDCl₃) δ 5.92 (s, 2H), 3.93 (s, 3H).    -   c)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        methyl carbonate.        (4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        sodium salt (100 mg, 0.227 mmol) and potassium carbonate (94 mg,        0.680 mmol) were suspended in water and tetrabutylammonium        hydrogen sulfate (77 mg, 0.227 mmol) was added followed by        dichloromethane. Stirring 5 min gave a clear biphasic solution.        Iodomethyl methyl carbonate (196 mg, 0.906 mmol) was added as a        solution in dichloromethane. Stirring 3 hours gave complete        reaction. The reaction was diluted with water, dichloromethane,        extracted with dichloromethane, washed with sodium bicarbonate,        brine, dried over sodium sulfate, and purified by silica-gel        chromatography (1-12% methanol/dichloromethane gradient        elution). The isolate was re-dissolved in ethyl acetate and        washed 4 times with water, and twice with brine, and dried over        sodium sulfate. Concentration under reduced pressure yielded the        title compound as a white solid. ¹H NMR (CDCl₃) δ 10.24 (m, 1H),        8.38 (s, 1H), 7.28 (m, 1H), 6.77 (m, 2H), 5.79 (m, 2H), 5.16 (m,        1H), 4.97 (m, 1H), 4.56 (d, J=6Hz, 2H), 4.25 (dd, J=13.2, 3.6        Hz, 1H), 4.13 (m, 1H), 3.92 (m, 2H), 3.76 (s, 3H), 2.13 (m, 1H),        1.46 (m, 1H), 1.29 (d, J=7.2 Hz, 3H). ES⁺MS: 508 (M+1).

Example 2{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(methyloxy)ethyl carbonate

The title compound was prepared from iodomethyl 2-(methyloxy)ethylcarbonate (59 mg, 0.227 mmol) (prepared in a similar manner to example1),(4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamidesodium salt (50 mg, 0.113 mmol), potassium carbonate (47 mg, 0.340mmol), and tetrabutylammonium hydrogen sulfate (39 mg, 0.113 mmol),using a similar process to that described in example 1. ¹H NMR (CDCl₃) δ10.32 (m, 1H), 8.37 (s, 1H), 7.31 (m, 1H), 6.77 (m, 2H), 5.83 (m, 2H),5.16 (m, 1H), 4.92 (m, 1H), 4.57 (d, J=6Hz, 2H), 4.29-4.23 (m, 3H), 4.16(m, 1H), 3.93 (m, 2H), 3.62-3.57 (m, 2H), 3.32 (s, 3H), 2.13 (m, 1H),1.46 (m, 1H), 1.30 (d, J=7.2 Hz, 3 H). ES⁺MS: 552 (M+1).

Example 3{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-hydroxyethyl carbonate

-   -   a)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        2-[(phenylmethyl)oxy]ethyl carbonate. The title compound was        prepared from iodomethyl 2-[(phenylmethyl)oxy]ethyl carbonate        (314 mg, 0.933 mmol) (prepared in a similar manner to example        1),        (4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        sodium salt (103 mg, 0.233 mmol), potassium carbonate (97 mg,        0.700 mmol), and tetrabutylammonium hydrogen sulfate (79 mg,        0.233 mmol), using a similar process to that described in        example 1. ¹H NMR (CDCl₃) δ 10.23 (m, 1 H), 8.36 (s, 1H),        7.33-7.23 (m, 6H), 6.78 (m, 2H), 5.84 (m, 2H), 5.13 (m, 1H),        4.88 (m, 1H), 4.57-4.51 (m, 4H), 4.30 (m, 2H), 4.21 (m, 1H),        4.10 (m, 1H), 3.88 (m, 2H), 3.72-3.66 (m, 2H), 2.08 (m, 1H),        1.40 (m, 1H), 1.25 (d, J=6.8 Hz, 3H). ES⁺MS: 628 (M+1).    -   b)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        2-hydroxyethyl carbonate. The product prepared as described in        step (a) above (125 mg, 0.199 mmol) was dissolved in        methanol/ethyl acetate mixture and 10 w.t. % palladium on carbon        (85 mg) was added under a nitrogen atmosphere. The reaction was        stirred at 1 atm hydrogen and then at 60 psi hydrogen for 14        hours. Acetic acid (1 mL) was added and the reaction was stirred        at 45 psi for 8 hours. The mixture was filtered through celite        and concentrated under reduced pressure. Purification by silica        gel chromatography yielded the title compound as a white solid.        ¹H NMR (CDCl₃) δ 10.12 (m, 1H), 8.35 (s, 1H), 7.32 (m, 1H), 6.78        (m, 2H), 5.92 (d, J=6.8 Hz, 1H), 5.85 (d, J=6.8 Hz, 1H), 5.17        (m, 1H), 4.88 (m, 1H), 4.58 (m, 2H), 4.38-4.29 (m, 2H), 4.23 (m,        1H), 4.11 (m, 1H), 3.93-3.82 (m, 4H), 3.29 (m, 1H), 2.14 (m,        1H), 1.49 (m, 1H), 1.33 (d, J=7.2 Hz, 3H). ES⁺MS: 538 (M+1).

Example 4{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(phosphonooxy)ethyl carbonate

-   -   a) 2-({Bis[(phenylmethyl)oxy]phosphoryl}oxy)ethyl        {[(4R,12aS)-9-({[(2,4-difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        carbonate. Dibenzyl N,N-diisopropyl-phosphoramidite was added to        a mixture of        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        2-hydroxyethyl carbonate (example 3) (43 mg, 0.080 mmol) and        tetrazole (67 mg, 0.960 mmol) in dichloromethane at ambient        temperature and stirred 14 hours. The reaction was cooled in an        ice-water bath, and m-CPBA (110 mg, 0.640 mmol) was added        carefully and the mixture was stirred for 30 minutes letting the        ice-bath expire. Sodium thiosulfate solution was added, and the        mixture was extracted with dichloromethane, washed with sodium        bicarbonate solution and brine, and dried over sodium sulfate.        Purification by silica gel chromatography afforded the title        compound as a white solid. ¹H NMR (CDCl₃) δ 10.22 (m, 1H), 8.33        (s, 1H), 7.32-7.26 (m, 11H), 6.78 (m, 2H), 5.83 (m, 2H), 5.10        (m, 1H), 5.02-4.98 (m, 4H), 4.87 (m, 1H), 4.57 (m, 2H), 4.29 (m,        2H), 4.21-4.13 (m, 3H), 4.00 (m, 1H), 3.90-3.86 (m, 2H), 2.07        (m, 1H), 1.39 (m, 1H), 1.25 (d, J=7.2 Hz, 3H). ES⁺ MS: 798        (M+1).    -   b)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        2-(phosphonooxy)ethyl carbonate. Product prepared as described        in step (a) above (52 mg, 0.065 mmol) was dissolved in methanol        and 10 w.t. % palladium on carbon (25 mg) was added and the        reaction was stirred under 1 atm hydrogen for 30 minutes. The        mixture was filtered through celite and concentrated under        reduced pressure to afford the title compound as a white solid.        ¹H NMR (methanol-d₄, CDCl₃) δ 10.19 (br s, 1H), 8.28 (br s, 1H),        7.32 (m, 1H), 6.70 (m, 2H), 5.64 (br s, 2H), 5.13 (br s, 1H),        4.81 (br s, 1H), 4.48-3.40 (m, 10H), 2.03 (m, 1H), 1.40 (m, 1H),        1.21 (m, 3H). ES″ MS: 616 (M−1).

Example 5{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(4-morpholinyl)ethyl carbonate hydrochloric acid salt

-   -   a) Chloromethyl 4-nitrophenyl carbonate. N-methyl morpholine        (1.24 mL, 11.24 mmol) was added dropwise to a solution of        4-nitrophenol (1.56 g, 11.24 mmol) in dichlormethane at 0° C.,        followed by dropwise addition of chloromethyl chloridocarbonate        (1 mL, 11.24 mmol) and the mixture was stirred for 14 hours at        ambient temperature. The reaction was diluted with citric acid        solution, extracted with dichloromethane, washed with aqueous        sodium bicarbonate, brine, and dried over sodium sulfate to        yield the title compound as a yellow oil. ¹H NMR (CDCl₃) δ 8.29        (m, 2H), 7.40 (m, 2H), 5.82 (s, 2H).    -   b) Iodomethyl 4-nitrophenyl carbonate. Chloromethyl        4-nitrophenyl carbonate (2.47 g, 10.67 mmol), sodium iodide        (1.76 g, 11.73 mmol) were suspended in acetone and heated        overnight at 45° C. The yellow suspension was allowed to cool to        ambient temperature, concentrated under reduced pressure,        diluted with water and aqueous sodium thiosulfate, extracted        with dichloromethane, washed with brine, dried over sodium        sulfate, and concentrated under reduced pressure to give the        title compound as a clear yellow oil. ¹H NMR (CDCl₃) δ 8.30 (dd,        J=7.2, 2.4 Hz, 2H), 7.42 (dd, J=6.8, 2 Hz, 2H), 6.06 (s, 2H).    -   c)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        4-nitrophenyl carbonate. The title compound was prepared from        (4R,12aS)—N-[(2,4-Difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazine-9-carboxamide        sodium salt (1.8 g, 4.29 mmol), iodomethyl 4-nitrophenyl        carbonate (2.77 g, 8.58 mmol), potassium carbonate (1.78 g,        12.88 mmol), and tetrabutylammonium hydrogen sulfate (1.46 g,        4.29 mmol) in a manner similar to that described in example 1,        step c. ¹H NMR (CDCl₃) δ 10.17 (m, 1H), 8.37 (s, 1H), 7.40 (m,        2H), 7.30 (m, 1H), 6.78 (m, 2H), 5.97 (d, J=6.4 Hz, 1H), 5.92        (d, J=6.4 Hz, 1H), 5.19 (m, 2H), 4.89 (m, 2H), 4.59 (m, 2H),        4.22 (m, 1H), 4.13 (m, 1H), 3.93 (m, 1H), 2.12 (m, 1 HO, 1.40        (m, 1H), 1.29 (m, 3H). ES⁺MS: 615 (M+1).    -   d)        {[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl        2-(4-morpholinyl)ethyl carbonate hydrochloric acid salt. A        mixture of intermediate prepared as described in step b (425 mg,        0692 mmol), 2-(4-morpholinyl)ethanol (excess), triethylamine        (0.29 mL, 2.08 mmol) and DMAP (84 mg, 0.692 mmol) in        acetonitrile was stirred at reflux for several hours. The        reaction was cooled and concentrated under reduced pressure,        diluted with water and dichloromethane, and extracted. The        combined organics were washed with aqueous sodium bicarbonate,        brine, and dried over sodium sulfate. Purification by        reverse-phase hplc afforded the title compound as the        trifluoroacetic acid salt. Re-dissolved isolate in        dichloromethane and washed organic layer with sodium bicarbonate        solution. Dried over sodium sulfate and concentrated under        reduced. The intermediate prepared as described above (124 mg,        0.204 mmol) was dissolved in dioxane and placed in an ice-water        bath. Hydrochloric acid (0.2 mL, 1N solution) was added and the        reaction was stirred 15 minutes at ambient temperature. The        mixture was concentrated under reduced pressure to yield the        title compound as a white solid. ¹H NMR (methanol-d₄/CDCl₃) δ        13.60 (m, 1H), 10.11 (m, 1H), 8.36 (s, 1H), 7.32 (m, 1H), 6.79        (m, 2H), 5.84 (m, 2H), 5.18 (m, 1H), 4.91 (m, 1H), 4.74 (m, 1H),        4.60 (m, 2H), 4.35-4.10 (m, 4H), 3.97-3.93 (m, 3H), 3.51 (m,        2H), 3.36 (m, 2H), 3.04 (m, 2H), 2.14 (m, 1H), 1.49 (m, 1H),        1.35 (m, 3H). ES⁺MS: 607 (M+1).

Example 6 Rat Pharmacokinetics

Fasted male CD rats received the compound of Example 2 as an oralsuspension dose (5 mg parent equivalent/kg in 0.1%hydroxypropylmethylcellulose/0.1% Tween-80) administered via an oralgavage needle. Blood samples (0.2 mL each) were drawn from a surgicallyimplanted femoral vein cannula at timed intervals for 24 h followingdose administration; all samples were drawn using EDTA-treated syringes.Each blood sample was combined with 0.02 mL of a protease inhibitorsolution [e-amino-n-caproic acid, benzamide HCl, and4-(2-aminoethyl)benzenesulfonyl fluoride HCl in water] to inhibit exvivo conversion of prodrug to parent, vortexed to mix, and centrifuged(4000×g, 4° C., 20 min) to harvest plasma. Prodrug and parentconcentrations in plasma samples were quantitated by LC/MS/MS analysis.Area under the plasma concentration-time curve was estimated usingnoncompartmental analysis methods (WinNonlin Professional 4.1)

1-15. (canceled)
 16. A compound of formula (I):

wherein: R¹ is C₁-C₈alkyl or LR²; L is alkylene; R² is a) hydroxy; b)alkoxy; c) OR³ wherein R³ is P(O)(OH)₂ or alkoxy; d) heterocyclyloptionally substituted with oxo or C₁-C₈alkyl; e) C(O)OR⁴ wherein R⁴ isH, C₁-C₈alkyl, or XR⁵ wherein X is alkylene and R⁵ is C₆-C₁₀aryl,heterocyclyl, or NR⁶R⁷ wherein R⁶ and R⁷ are independently selected fromthe group consisting of H and C₁-C₈alkyl; f) NR⁶R7⁷; g) C(O)NR⁸R⁹wherein R⁸ and R⁹ are independently selected from the group consistingof H and XR⁵; or h) C(O)R¹⁰ wherein R¹⁰ is heterocyclyl optionallysubstituted with XR¹¹ wherein R¹¹ is heterocyclyl; or a pharmaceuticallyacceptable salt thereof.
 17. A compound of formula (I) according toclaim 16 wherein R¹ is C₁₋₈alkyl.
 18. A compound of formula (I)according to claim 16 wherein R¹ is LR² wherein L is C₁₋₈alkylene and R²is hydroxy or alkoxy.
 19. A compound of formula (I) according to claim16 wherein R¹ is LR² wherein L is C₁₋₈ alkylene and R² and —OP(O)(OH)₂or a pharmaceutically acceptable salt thereof.
 20. A compound of formula(I) according to claim 16 wherein R¹ is LR² wherein L is C₁₋₈alkyleneand R² and heterocyclyl or a pharmaceutically acceptable salt thereof.21. A compound selected from the group consisting of:{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methylmethyl carbonate;{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(methyloxy)ethyl carbonate;{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-hydroxyethyl carbonate;{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(phosphonooxy)ethyl carbonate;{[(4R,12aS)-9-({[(2,4-Difluorophenyl)methyl]amino}carbonyl)-4-methyl-6,8-dioxo-3,4,6,8,12,12a-hexahydro-2H-pyrido[1′,2′:4,5]pyrazino[2,1-b][1,3]oxazin-7-yl]oxy}methyl2-(4-morpholinyl)ethyl carbonate; and pharmaceutically acceptable saltsthereof.
 22. A compound according to any one of claims 16 to 21 whereinthe pharmaceutically acceptable salt is a hydrochloride salt.
 23. Amethod of treatment of a viral infection in a human comprisingadministering to said human an antiviral effective amount of a compoundaccording to any one of claims 16 to
 21. 24. A method according to claim23 wherein the viral infection is a HIV infection.
 25. A methodaccording to claim 23 wherein the pharmaceutically acceptable salt is ahydrochloride salt.
 26. A pharmaceutical composition comprising aneffective amount of a compound according to any one of claims 16 to 21together with a pharmaceutically acceptable carrier.
 27. Apharmaceutical composition according to claim 26 in the form of atablet, capsule, liquid or suspension.
 28. A pharmaceutical compositionaccording to claim 26 wherein the pharmaceutically acceptable salt is ahydrochloride salt.
 29. A method of treatment of a HIV infection in ahuman comprising administering to said human a composition comprising acompound according to any one of claims 16 to 21 and another therapeuticagent.